The effects of various prostaglandins have been studied utilizing separated proximal tubules from rabbit kidney. No effects have been found of prostaglandins of the A and E series on sodium, potassium, chloride and water transport of separated rabbit proximal tubules. Additionally, no effects were noted in guinea pig and rat cortical slice preparations. Alpha and beta adrenergic agonists and antagonists do not affect these systems when the transport of the above mentioned substances is measured. Cyclic AMP and cyclic GMP are also without effect. We conclude that the effects of these agents on sodium transport in the intact kidney is a result of their effects on the renal vasculature and the post-glomerular physical forces rather than directly upon the sodium transport process.